docs: def fulfill(self,
                  agreement_id,
                  amount,
                  receiver_address,
                  sender_address,
                  lock_condition_id,
                  release_condition_id,
                  account):
          """
          Fulfill the escrow reward condition.
  
          :param agreement_id: id of the agreement, hex str
          :param amount: Amount of tokens, int
          :param receiver_address: ethereum address of the receiver, hex str
          :param sender_address: ethereum address of the sender, hex str
          :param lock_condition_id: id of the condition, str
          :param release_condition_id: id of the condition, str
          :param account: Account instance
          :return:
          """
          return self._fulfill(
              agreement_id,
              amount,
              receiver_address,
              sender_address,
              lock_condition_id,
              release_condition_id,
              transact={'from': account.address,
                        'passphrase': account.password}
          )